How to model the bottle threads?
Using a screw modifier and knife boolean


Start off with a cylinder. Duplicate one polygon and separate it off into its own object.
Extrude the face out into a box.  Make loop cuts in the box.  Select one face at a normal to the cylinder then invert the selection and delete all the other faces.  You should have a face that's aligned with the cylinder edge and at a normal to it.

Add a Screw modifier.  Ensure the number of steps agrees with the number of sides on the cylinder.  Adjust the settings until you have the desired spiral for your thread.  Apply the modifier.

Join the screw and cylinder objects into one mesh.  In edit mode, select the cylinder polygons and click Intersect (Knife) on the Face specials menu.  The screw polygons are no longer required so can be deleted.

Add a couple of edge loops to the main thread spiral.  Then use the inset polygon tool to bevel out the thread itself.  Adjust the start and end of the thread so there is a smooth transition.



The resulting topology leaves 4 ngons, but I like how they subdivide so I leave them in. Converting to all quads is possible with some thought.



The final render